The invention concerns a linear motion guide having a guide rail and a slide supported on the guide rail by way of rolling or roller elements, where the guide rail is provided with coverable through holes for fastening elements for mounting of the guide rail on a support, which holes open in a surface of the guide rail facing away from the support and which are arranged in the region of motion of the slide.
Linear motion guides are regularly used for the linear guidance of components with high precision such as, for example, for the guidance of mechanical subassemblies on machine tools or for the motion of measuring heads. Linear motion guides are also used in environments with a high degree of fouling. To prevent the rolling or roller elements arranged in the slide from fouling, which would lead to high wear as well as possibly to the loss of guide precision, steps are taken to prevent the penetration of dirt or dust into the interior of the slide. For this purpose lip seals, which slide along the surface of the guide rails as well as of the side faces of the guide rails, are frequently provided on the two front faces of the slide perpendicular to the direction of travel, in order to wipe particles of dust or dirt from the respective surface.
For fastening the guide rail of a common linear motion guide, the guide rail is provided with through holes for appropriate fastening elements for mounting the guide rail on a support. The through hole may, for example, be recessed for the accommodation of a fastening screw with screw head. Since dust and dirt that may possibly get into the interior of the guide slide when the latter is directly over the hole may accumulate between the top side of the screw head and the surface of the guide rail, it is disclosed in DE 3,812,505 A1 that in a generic linear motion guide the through holes on the surface may be covered, specifically, by means of a striplike plate which is inserted in a longitudinal groove on the top side of the guide rail corresponding to the plate cross section and which is bolted fast to the guide rail by retaining means at either end of the plate. For this, a corresponding fastening screw passes through an associated through hole of the plate before it penetrates into a corresponding thread of the guide rail.
DE 3,812,505 A1 describes as known another type of covering wherein the longitudinal groove is designed continuous and is provided with a profile in order to hold the plate, inserted into the longitudinal groove from one end of the guide rail, in the said longitudinal groove. Here, however, the risk exists that in case of great sliding resistance of the wiping seal the plate may possibly be carried along in the longitudinal direction of the guide rail. In both known linear motion guides, not only is the relatively high structural cost, because of the longitudinal groove to be worked into the guide rail, a disadvantage, but so is the practically unavoidable design of a small step or narrow slot between the longitudinal edges of the plate and the edges between the surface and the grooved side faces. The wiping seal slides along the guide rail at this beveled step or the beveled edges of the slot possibly having a varying slot width, specifically as a rule under relatively high pressure, in order to ensure that the top side of the guide rail, particularly susceptible to fouling, is reliably wiped. Nevertheless, this does not always ensure that dirt particles in the edge region or slot region do not get into the interior of the slide.